of dendrochronology comprises various types of analyses on
of trees, tree rings. One of the main principles of dendrochronology is cross-dating. Dendrochronologists
analyze tree-rings by their common growth behaviour and, as initial step
analyses, cross-match the wide and narrow tree-rings among the array of
samples. One tree-ring chronology may consist of tens or
hundreds, even thousands, of
individual tree-ring series of the
species from a given region. Series are
averaged annually to form reliable records of past growth
to cross-dating, tree-ring chronology becomes dated with absolute accuracy.
and environmental factors influence the growth of tree-rings from
time-scales. This creates possibility to date the past climatic
and environmental events with
possible precision of all geological
Tree-ring research conducted at the
Department of Geosciences and Geography has its roots in the
study of subfossil pinewood archives. Scots pine (Pinus
L.) megafossils remain preserved in the bottom sediments
small lakes, peat bogs
and as dead standing trees (snags). Additional tree-ring material can
obtained from historical buildings. Theory of cross-dating is a key to
composite chronologies from living,
historical and subfossil tree-rings. Megafossil
collection from northernmost Lapland
covers the past 76
centuries being one of the longest continuous tree-ring
chronologies in the world. At the same time,
this chronology is probably the
longest absolutely dated and annually resolved temperature proxy
collection was largely intensified in the 1990s in collaboration with
Institute and SAIMA Centre for Environmental Sciences. Over those
the research was led by the professor Matti Eronen (1944-2016) who had
started the research of collecting subfossil pine samples in Finnish
Lapland already in the early 1970s. Since
then, the tree-ring
research has continued to focus primarily on climatic and
palaeoclimatic targets. Meanwhile, the research topics have also
increased in number to cover the different subfields of
dendrochronology. This research has been
conducted by those researchers who share the collegial
identification of the this dendrochronological school. Samuli
Helama is currently at the
Natural Resources Institute, Rovaniemi, and also acting as a docent at
the department. Jari Holopainen has
recently continued his activities at
the University of Eastern Finland. Marc
Macias-Fauria is acting as
an associate professor at the University
of Oxford. Morever, Alar Läänelaid, whose dissertation work was the first tree-ring based
PhD thesis at the department, acts as an associate professor at the
University of Tartu.
More recently, this tree-ring work
continued under the CARATE- ja QUANOMAL-projects (link), funded by the Academy of Finland, which have
been research consortiums between the Laboratory of Chronology (Univeristy of Helsinki) and the Natural Resources
Institute Finland. These projects
have advanced the use of Finnish dendrochronological archives to
analyse isotopes from cross-dated tree-ring cellulose, to build long
stable carbon (13C) and oxygen (18O) and of
radiocarbon (14C) to
infer the changes in plant ecophysiology, and to assess past and
variability and the historical/prehistoric solar superstroms.
Importantly, this work has built on the legacy of subfossil tree-ring
analyses that now itself has an intellectual, departmental history of
nearly half a century.
The basis of our dendrochronological
is the compound interpretation of living tree and subfossil
variability and factors behind their behaviour. The research can be
divided into several
different subfields as follows:
constructing new tree-ring chronologies
studying the relationships between tree-rings and climate
studying the relationships between tree-rings and ecological factors
reconstructing the past climates using tree-ring chronologies
interpreting the past environments from tree-ring based records
analysis is used in all aforementioned (1-5) subfields of
Students aiming for
dendrochronological thesis (Bachelor, Master, Licentiate or
Ph.D.) should familiarize
himself/herself with at
least the basic concepts of time-series analysis!
Lecture course in Dendrochronology,
54252, has been lectured at the Department of
Geosciences and Geography, several times over the past years.
Teaching language of the course has been, most recently, English (link).
processes and large-scale climate relationships in northern coniferous
Marc Macias Fauria
of past climates from documentary and natural sources
the 18th century"
tree-ring chronologies as records of climate variability in Finland"
Tree-ring dating in Estonia"
Speer, J. 2010. Fundamentals of Tree-Ring Reearch. University of
Arizona Press, 333 p.
Cook E.R. &
(Editors) 1990: Methods of
Dendrochronology. Kluwer Academic Publishers, 394 pp.
Hughes M.K., Kelly
P.M., Pilcher J.R., Lamarche
V.C., Jr. (Editors) 1982: Climate from tree rings. Cambridge University
Press, 223 pp.
Fritts H.C. 1976:
Tree Rings and
Academic Press, 567 pp.